object-oriented C by Henry Kroll III www.thenerdshow.com, C (gcc)

object-oriented C by Henry Kroll III www.thenerdshow.com

//gcc 4.9.3
//object-oriented C Copyright(C) 2016 Henry Kroll III www.thenerdshow.com
//usr/local/bin/anch -std=c99 -keep -run "$0" "$@" ; exit $?
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>

//list the types
#define TYPELIST                                                       \
X(int, "%i")                                                           \
X(float, "%3.1lf")                                                     \
X(double, "%3.1lf")                                                    \
X(char, "'%c'")

//unify the types
#define X(type, fmt) type *type##_t;
typedef union { TYPELIST } utype;
#undef X

//dope vector "object" template
typedef struct obj {
    char *name;
    size_t pos, length;
    //methods
    utype *(*iter)(struct obj *);
    void (*increment)(struct obj *);
    void (*decrement)(struct obj *);
    void (*print)(struct obj *);
    #define X(type, fmt) type *type##_ptr;
 union{TYPELIST};
    #undef X
 char mem;
} obj, *object;
//template expands methods for each type
#define X(type, fmt)                                                   \
utype *iter_##type (object d) {                                        \
    return d->pos < d->length?(utype*)&d->type##_ptr[d->pos++]:NULL;   \
}                                                                      \
void increment_##type (object d) {                                     \
    for(int i=d->length;i--;) d->type##_ptr[i]++;                      \
}                                                                      \
void decrement_##type (object d) {                                     \
    for(int i=d->length;i--;) d->type##_ptr[i]--;                      \
}                                                                      \
void print_##type (object d) {                                         \
    printf(#type " %s={", d->name);                                    \
    for(int i=0;i<d->length;i++)                                       \
        printf(fmt ",", d->type##_ptr[i]);                             \
    puts("}");                                                         \
}
TYPELIST;
#undef X

/* define some global object prototypes (classes)
 * containing pre-packaged methods for each type of object
 * NEW objects will be mem copied (inherited) from these classes
 */
#define X(type, fmt)                                                   \
obj type##_obj={"", 0, 0,                                              \
iter_##type, increment_##type, decrement_##type, print_##type };
TYPELIST;
#undef X

//convenience macros for dot.objects (dope wrappers)
//define a new local variable and wrap it into a dot.object class
#define NEW_dot(type, id, len, ...) type id##_data[]={__VA_ARGS__};    \
obj id = type##_obj; id.name = #id,                                    \
id.length = len, id.type##_ptr = id##_data;
#define F_dot(a, b) b.a(&(b))
#define NEXT_dot(b) *F_dot(iter, b)

//convenience macros for arrow->objects (dope objects)
/* allocate enough NEW memory for the struct + contents
 * copy (inherit) new object from object's prototype (class)
 * initialize object's pointer to its internal memory
 * copy any supplied data into the new object */
#define NEW(alloc, type, id, len, ...)                                 \
object id = alloc(sizeof *id + len * sizeof(type));                    \
*id = type##_obj, id->name = #id, id->length = len,                    \
id->type##_ptr = (type*)&id->mem; /* point to internal memory */       \
type id##_tmp[]={__VA_ARGS__}; /* copy data into object */             \
memcpy(id->type##_ptr, &id##_tmp, len * sizeof(type));
#define F(a, b) b->a((b))
#define NEXT(b) *F(iter, b)
//main
int main (void) {
    //"dot" objects are declared in local scope
    NEW_dot(int,   idot, 5, 1,2,3,4,5);
    NEW_dot(double,fdot, 3, 0.0, 4.5, 2.7);
    NEW(malloc, float, farr, 3, 2.1, 2.5, 2.7);
    NEW_dot(char,  cdot, 4, "uijt");
    //F_dot function wrapper hides ugly object.method(&object) calls
    idot.increment(&idot);
    F_dot(increment, idot);
    F_dot(decrement, cdot);
    F_dot(decrement, fdot);
    F_dot(print, idot);
    F_dot(print, fdot);
    F_dot(print, cdot);
    //F function hides ugly object->method(object) calls
    farr->increment(farr);
    F(increment, farr);
    //iter method can be invoked several ways
    //accessing .iter directly
    printf ("%i ", *idot.iter(&idot));
    //using F_dot function macro
    printf ("%i ", *F_dot(iter, idot));
    //using NEXT_dot iter macro
    printf ("%i ", NEXT_dot(idot));
    //non-int types still require awkward recast to actually use
    printf ("%3.1lf ", *(double*)&NEXT_dot(fdot));
    printf ("%3.1lf ", *(double*)&NEXT_dot(fdot));
    printf ("%3.1f ", *(float*)&NEXT(farr));
    printf ("%3.1f ", *(float*)&NEXT(farr));
    printf ("%c ", NEXT_dot(cdot));
    printf ("%c ", NEXT_dot(cdot));
    printf ("%c ", NEXT_dot(cdot));
    printf ("%c ", NEXT_dot(cdot));
    free (farr);
    return 0;
}


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